1. Field of the Invention
A vehicle steering mechanism includes a wire device connected between fixed and movable column members for absorbing the energy forces applied thereto upon impact, and force generating means for varying the frictional resistance developed by the wire as a result of the physical properties of the driver, the vehicle, and/or the environment of vehicle use.
2. Description of the Related Art
This invention relates to an infinitely modulatable energy absorption device for an automotive vehicle steering column, which absorption device is operable axially of the direction of collapse of the steering column.
The device according to the invention is used especially on a steering column that can be adjusted in terms of depth and/or inclination, which steering shaft is mounted in a tubular body that is supported and locked on the vehicle chassis at the desired position. The steering column comprises a steering shaft that is mounted so that it can rotate in the tubular body, which body is linked to a support assembly attached upon the vehicle chassis or upon an element of the car body. The invention can also be used for an nonadjustable steering column; in this case, the tubular body is mounted directly in the support assembly.
During impact of the vehicle, a portion of the impact energy of the driver upon the steering wheel is absorbed by the steering column. The latter, in general, comprises systems that make it possible to cushion the movement of the driver at the moment of impact upon the steering wheel. The systems that are currently installed on mass-produced vehicles will react according to inflexible pre-established rules, regardless of the conditions involved in the impact.
In reality, the amount of energy necessary to brake the momentum of the driver in case of impact will depend on several parameters, such as the speed of the vehicle, the weight of the driver, the wearing of a seat belt, and the like, which are not taken into account by the energy absorption systems of the prior art.
These systems penalize certain categories of drivers who are not included in the average population for which the energy absorption element upon the steering column was calibrated. These categories generally are persons of small size, and persons of very large size. As a matter of fact, a small-framed person meeting a rigid obstacle often results in the risk of inflicting bodily damage upon said person, and a large-framed person is not sufficiently slowed down and faces the risk of suffering damage due to an excessive acceleration of his body during the crash.
Systems that take into account certain parameters, such as the wearing of the seatbelt or the weight of the driver, have been proposed by the applicant and are covered in French Patents Nos. 99-00169, 99-14813, and 00-09815. These concepts make it possible to have a discrete number of rules as a function of the number of elements of energy absorption present on the steering column.
This improves the absorption of the energy, but does not cover all impact situations where certain parameters are specific to each accident case, such as the speed of the vehicle before the impact.